Mod_sonar can be useful for collecting specific round trip delay information about a call route. This is a first working draft, so expect it to interfere with the migration habits of your creatures. To use setup a destination with echo, originate a call to that destination and drop the call into &sonar(). Then watch the logs for the results.

src/mod/applications/mod_sonar/Makefile

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+BASE=../../../..
+include $(BASE)/build/modmake.rules

src/mod/applications/mod_sonar/mod_sonar.c

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+/* 
+ * FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
+ * Copyright (C) 2005-2012, Anthony Minessale II <anthm@freeswitch.org>
+ *
+ * Version: MPL 1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
+ *
+ * The Initial Developer of the Original Code is
+ * Anthony Minessale II <anthm@freeswitch.org>
+ * Portions created by the Initial Developer are Copyright (C)
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ * 
+ * William King <william.king@quentustech.com>
+ *
+ * mod_sonar.c -- Sonar ping timer
+ *
+ * 
+ */
+
+/*
+  TODO:
+  1. Use libteltone directly
+  2. Use an energy detection to listen for first set of sound back. Use timestamp of detection of energy as the recv stamp if a tone is eventually detected.
+  3. Check for milliwatt pings. Listen for frequency changes, and audio loss
+ */
+
+
+#include <switch.h>
+
+/* Prototypes */
+SWITCH_MODULE_SHUTDOWN_FUNCTION(mod_sonar_shutdown);
+SWITCH_MODULE_RUNTIME_FUNCTION(mod_sonar_runtime);
+SWITCH_MODULE_LOAD_FUNCTION(mod_sonar_load);
+
+/* SWITCH_MODULE_DEFINITION(name, load, shutdown, runtime) 
+ * Defines a switch_loadable_module_function_table_t and a static const char[] modname
+ */
+SWITCH_MODULE_DEFINITION(mod_sonar, mod_sonar_load, mod_sonar_shutdown, NULL);
+
+switch_time_t start, end, diff;
+
+switch_bool_t sonar_ping_callback(switch_core_session_t *session, const char *app, const char *app_data){
+	
+	if ( end ) {
+		return SWITCH_TRUE;
+	}
+	
+	end = switch_time_now();
+	diff = end - start;
+	start = 0;
+	switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_NOTICE, "Sonar ping took %lu milliseconds\n", diff / 1000);	
+	
+	return SWITCH_TRUE;
+}
+
+SWITCH_STANDARD_APP(sonar_app)
+{
+	switch_channel_t *channel = switch_core_session_get_channel(session);
+	char *tone = "%(500,0,1004)";
+	int loops = atoi(data);
+	
+	if ( ! loops ) {
+		loops = 5;
+	}
+	
+	switch_channel_answer(channel);
+	switch_ivr_sleep(session, 1000, SWITCH_FALSE, NULL);
+	
+	switch_ivr_tone_detect_session(session, 
+								   "ping", "1004",
+								   "r", 0, 
+								   1, NULL, NULL, sonar_ping_callback);
+	
+	switch_ivr_sleep(session, 1000, SWITCH_FALSE, NULL);
+
+	for( int x = 0; x < loops; x++ ) {
+		end = 0;
+		start = switch_time_now();
+		switch_ivr_gentones(session, tone, 1, NULL);
+		switch_ivr_sleep(session, 2000, SWITCH_FALSE, NULL);
+		if ( start ) {
+			switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_NOTICE, "Lost sonar ping\n");			
+		}
+	}
+	
+	switch_ivr_sleep(session, 1000, SWITCH_FALSE, NULL);
+	switch_ivr_stop_tone_detect_session(session);
+}
+
+/* Macro expands to: switch_status_t mod_sonar_load(switch_loadable_module_interface_t **module_interface, switch_memory_pool_t *pool) */
+SWITCH_MODULE_LOAD_FUNCTION(mod_sonar_load)
+{
+	switch_application_interface_t *app_interface;
+
+	/* connect my internal structure to the blank pointer passed to me */
+	*module_interface = switch_loadable_module_create_module_interface(pool, modname);
+
+	SWITCH_ADD_APP(app_interface, "sonar", "sonar", "sonar", sonar_app, "", SAF_NONE);
+
+	/* indicate that the module should continue to be loaded */
+	return SWITCH_STATUS_SUCCESS;
+}
+
+/*
+  Called when the system shuts down
+  Macro expands to: switch_status_t mod_sonar_shutdown() */
+SWITCH_MODULE_SHUTDOWN_FUNCTION(mod_sonar_shutdown)
+{
+
+	return SWITCH_STATUS_SUCCESS;
+}
+
+
+/* For Emacs:
+ * Local Variables:
+ * mode:c
+ * indent-tabs-mode:t
+ * tab-width:4
+ * c-basic-offset:4
+ * End:
+ * For VIM:
+ * vim:set softtabstop=4 shiftwidth=4 tabstop=4
+ */